Using $2.93~\mathrm{ fb}^{ -1}$ of $e^+e^-$ annihilation data collected at a center-of-mass energy $\sqrt{ s}=3.773$ GeV with the BESIII detector operating at the BEPCII collider, we search for the semileptonic $D^{ 0(+)}$ decays into a $b_1(1235)^{ -(0)}$ axial-vector meson for the first time. No significant signal is observed for either charge combination. The upper limits on the product branching fractions are ${ \mathcal B}_{ D^0\to b_1(1235)^- e^+\nu_e}\cdot { \mathcal B}_{ b_1(1235)^-\to \omega\pi^-}<1.12\times 10^{ -4}$ and ${ \mathcal B}_{ D^+\to b_1(1235)^0 e^+\nu_e}\cdot { \mathcal B}_{ b_1(1235)^0\to \omega\pi^0}<1.75\times 10^{ -4}$ at the 90\% confidence level.
Categories: hep-ex